/*
 * Copyright [2013-2021], Alibaba Group Holding Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.alibaba.polardbx.optimizer.core.function.calc.scalar.control;

import com.alibaba.polardbx.optimizer.context.ExecutionContext;
import com.alibaba.polardbx.optimizer.core.datatype.DataType;
import com.alibaba.polardbx.optimizer.core.function.calc.AbstractScalarFunction;
import com.alibaba.polardbx.optimizer.utils.FunctionUtils;

import java.util.List;

/**
 * Created by chuanqin on 17/8/25.
 */
public class CaseV2 extends AbstractScalarFunction {
    public CaseV2(List<DataType> operandTypes, DataType resultType) {
        super(operandTypes, resultType);
    }

    @Override
    public Object compute(Object[] args, ExecutionContext ec) {
        Object then = args[args.length - 1];

        // Searched CASE expression
        // (null, when, then)
        // (null, when, then, else)
        // (null, when, then, when, then)
        // (null, when, then, when, then, else)
        for (int i = 0, len = args.length - 2; i < len; i += 2) {
            Object when = args[i];
            if (FunctionUtils.convertConditionToBoolean(when)) {
                then = args[i + 1];
                break;
            }
        }
        return then;
    }

  @Override
  public String[] getFunctionNames() {
    return new String[] { "CASE" };
  }
}
